JP2007122704A - Method and apparatus for partitioning industrial control data - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a logical reference to a subset of unformatted data block (115, 120) including at least a portion of I/O data for an associated I/O module (30). <P>SOLUTION: An industrial controller (15) includes a processing unit 16 and a memory (17). The industrial controller (15) is operable to communicate using an optimized connection packet (100) including I/O data from a plurality of I/O modules (30) arranged as the unstructured data block (115, 120). The processing unit (16) is operable to operate on the I/O data within the optimized connection packet 100 to control a process. The memory (17) is operable to store a plurality of cast tags (125). Each cast tag (125) is associated with one of the I/O modules (30). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates generally to automatic control systems, and more particularly to a method and apparatus for segmenting industrial control data.

  An industrial controller is a special purpose computer used to control an industrial process or manufacturing equipment. The industrial controller, in accordance with stored program instructions, examines a series of input signals representing the status of the process being controlled, and modifies output signals that affect process control. The input and output signals may be binary (ie, on or off) signals, or alternatively, analog input / output signals that take a continuous range of values may be used. Two-entry output signals can be displayed with single bit data, and analog input / output signals can be displayed with multiple bit data words.

  The various parts of an industrial controller are often spatially distributed around a factory or manufacturing facility that is to be interconnected by one or more communication networks. These communication networks are characterized by being highly reliable and sending data with a well-defined minimum delay time as required for real-time control. Industrial controller technology typically uses a number of different communication networks, including but not limited to ControlNet® DeviceNet® and EtherNet / IP®. The specifications for the above communication networks have been published and their protocols are widely used by many manufacturers and suppliers. These communication networks have physical characteristics such as media type (eg coaxial cable, twisted pair, fiber optic, etc.), operational protocol (baud rate, number of channels, word transmission size, connection message usage, etc.), data Are different from each other in terms of how they are formatted and how data is collected into standard messages.

  A common component in an industrial control system is an input or output (I / O) module, which captures data for an industrial controller from a controlled process or machine and from the industrial controller to the controlled process. Or data is provided to the device. As described above, the I / O module is separated from the industrial controller and is connected via a communication network.

  Various I / O modules used in industrial control systems can generate data at different intervals and frequencies. As each controller generates its data, assuming that the controller is asynchronously interfaced with the I / O module, the control system encounters a problem in synchronizing its control operations and Traffic becomes difficult to handle. For example, the controller does not require data from a particular I / O module at the same frequency that the module generates data. Assuming that the I / O module sends a transaction to the controller each time it updates its data, the controller is required to handle transactions for data that the controller does not need for the current control decision.

  Scanner as a physical or logical relay between the I / O module and the controller to optimize network traffic, convert and proxy between different network types, and generate synchronous data transfer frames Can be used. The scanner collects data at a given update interval, consolidates this data into a single optimized connection packet, and forwards the optimized connection packet to the controller using one transaction per update interval To interface with the I / O module. Thus, assuming that the controller needs data for control decision purposes, it receives data at a controlled predetermined interval.

  In generating optimized connection packets, the scanner periodically sends optimized connection packets to the controller. An optimized connection packet is a block of unstructured data that represents data collected from each of the I / O modules. Data from each module is concatenated in a predetermined order without formatting. The optimized connection packet configuration is determined in advance. This predetermined configuration is used by the control application and program development system (ie, used to develop the control application) before referring to the data in the optimized connection packet. For example, if the output of a particular I / O module is present in bits NK of the optimized connection packet, the program instructions in the control application are exactly these for use in generating a control decision. Refers to the bit.

  When developing a control application, the application developer must know about optimized connection packet mapping. Within the program commands that make up the control application, a fixed reference to the parts of the optimized connection packet is included. If the optimized connection packet mapping changes due to the addition or deletion of I / O modules, the order of the I / O modules serviced by the scanner etc. so that the controller refers to the appropriate data, That is, the fixed reference must be updated in the control application.

  Imposing a fixed reference structure for optimized connection packets results in various problems for control application developers with respect to program maintenance and integrity. Documentation of data used in programmatic references can be unrealistic or inefficient. Thus, the task of updating the program reference when a program needs to be modified is difficult, inaccurate and time consuming.

  One technique for solving the problems arising from optimized connection packets is to copy the combined packets to individual locations. These individual locations can be more easily referenced by the control program. However, the same configuration control issues exist for converting between optimized connection packets and individual locations. This technique also requires program maintenance, introduces copy delays, and may have to compromise data integrity.

  This section of the specification describes various features of the technology that may be related to various features of the invention described and / or claimed below. This section provides background information to facilitate a better understanding of the various features of the present invention, and the statements in this section of the specification are not an admission of prior art and are described above. In view, it should be understood that it should be read.

  One feature of the present invention is that found in an industrial controller that includes a processing unit and a memory. The industrial controller is adapted to communicate using optimized connection packets containing I / O data from multiple I / O modules arranged as unstructured data blocks. . The processing unit is operable to operate on the I / O data in the optimized connection packet to control the process. The memory is operable to store a plurality of cast tags, each cast tag being associated with one of the I / O modules and storing at least a portion of the I / O data for the associated I / O module. Provide a logical reference to the subset of unformatted data blocks that it contains.

  Another feature of the present invention is found in a method for referencing industrial control data. The method includes exchanging I / O data with a plurality of I / O modules. An optimized connection packet is generated that includes I / O data for each module located in the unformatted data block and a plurality of cast tags are defined. Each cast tag is associated with one of the I / O modules and provides a logical reference to a subset of the unformatted data block that includes at least some of the I / O data for the associated I / O module. provide.

Yet another aspect of the invention is found in an industrial control system that includes a plurality of I / O modules, a scanner, and an industrial controller. These I / O modules operate to interface with the process to exchange I / O data with the process. The scanner exchanges I / O data with the I / O modules and communicates using optimized connection packets containing I / O data for each module located in the unformatted data block Can operate to do. The industrial controller is operable to exchange optimized connection packets with the scanner and to control the process using the I / O data contained within the optimized connection packets. The industrial controller is further operable to store a plurality of cast tags, each cast tag associated with one of the I / O modules and the I / O data for the associated I / O module. Providing a logical reference to a subset of unformatted data blocks including at least a portion.
The present invention will now be described with reference to the accompanying drawings, wherein like reference numerals indicate like parts throughout the drawings.

  The present invention is susceptible to various modifications and changes. Although specific embodiments of the present invention have been described by way of example shown in the drawings, the present invention will be further described in detail. However, the description of specific embodiments is not intended to limit the invention to the specific forms disclosed, but rather covers all modifications and equivalents falling within the spirit of the invention as defined by the claims. Should be understood.

  The following describes one or more specific embodiments of the present invention. The present invention is not limited to the examples and representations described herein, but is a variation of some of the examples that fall within the scope of the claims and combinations of components of different examples. Includes form. In developing such actual implementations, as in engineering or design projects, achieve the developer's specific goals, for example, compliance with system-related and business-related restrictions that may vary from implementation to implementation. However, many implementation specific decisions must be made. Moreover, such development efforts are complex and time consuming, but nevertheless are not design, manufacturing and product routine planning for those skilled in the art to benefit from this specification. Should be understood. Unless stated to be important or essential, nothing in this application is deemed to be critical or essential to the invention.

  Referring now to the accompanying drawings, wherein like reference numerals are used to refer to like parts throughout the several views, the present invention will be described with particular reference to FIG. To do. In general, the industrial control system 10 includes an industrial controller 15 (eg, a programmable logic controller (PLC)) that includes a processing unit 16 and a memory 17, a programming terminal 20, a human-machine interface (HMI) 25, and an I / O. Modules 30 and 35, a sensor 40, an actuator 45, scanners 50 and 55, and communication media 60, 65 and 70 are provided.

  The programming terminal 20 enables configuration, modification, debugging and maintenance of the industrial control system 10. For example, the programming terminal 20 can communicate with the industrial controller 15 to change the operating characteristics of the controller, for example the control program stored in the memory 17 and executed by the processing unit 16. The HMI 25 provides an operator interface for operating the industrial control system 10 and performing automated industrial processes.

  As will be described in more detail below, the programming terminal 20 defines a cast tag that can be used to overlay the data structure on unstructured data sent between the industrial controller 15 and the scanners 50,55. These cast tags are used by other entities in the industrial control system 10, such as the industrial controller 15 or the HMI 25, for an unstructured data block without prior knowledge of the predetermined structure of the data. Individual subsets can be logically referenced. Therefore, even if a data object is embedded in an unstructured data block containing data from multiple modules, it is maintained by the I / O module that indicates the configuration and state of the I / O module 30. Cast tags can be used to logically reference data objects.

  The I / O modules 30, 35 provide an interface to sensors 40 and actuators 45 related to the process being controlled. The sensor 40 can detect parameters such as fluid temperature, pressure, flow rate, torque, and current. The actuator 45 controls a fan, a beater, a pump, and the like such as a motor and a valve related to the robot system. For example, one type of actuator 45 is a motor drive that is adapted to generate a variable frequency drive signal for driving an associated motor. For ease of explanation, the individual sensors 40 and actuators 45 are not shown for all of the I / O modules 30, 35.

  In the industrial controller 15, input signals from the I / O modules 30 and 35 are processed by a control program, and further the signals are sent as output signals (for example, to the actuator 45). For the present invention, the particular process being controlled and the particular type of input / output module are not critical. The I / O modules 30 and 35 may be integrated with the industrial controller 15 or may be separated from the industrial controller 15. In one embodiment, the industrial control system 10 can be implemented using Logix® components provided by Rockwell Automation, Milwaukee, Wis., USA.

  Communication media 60, 65, 70 may take the form of a cable, may be a separate wire, or may include a digital network that may also include repeaters, routers, bridges, and gateways. Suitable communication media 60, 65, 70 may include DeviceNet®, Ethernet / IP® or ControllNet® networks, which are also provided by Rockwell Automation.

  As shown in FIG. 1, the I / O module 30 is connected as a subnet (communication medium 70) under the scanner 50. The scanner 50 serves as a relay between the I / O module 30 and the industrial controller 15. The scanner 55 is also connected to the communication media 60, but the associated I / O module 35 is coupled under the scanner 55 using a separate channel (communication media 65) to communicate with the scanner 55. .

  The scanners 50, 55 are for converting from one communication protocol (eg, used in communication media 60) to another protocol (eg, used in channel (communication media 65) or subnet (communication media 70)). It can also operate as a router. The structure of the scanners 50, 55 is also provided to illustrate the different techniques for interfacing the I / O modules in the system 10. An actual implementation may include only one scanner 50, 55 that uses one of the illustrated interface structure or another interface structure. For ease of explanation, the following description refers to scanner 50, but these techniques are equally applicable to both scanners 50 and 55.

  In the illustrated embodiment, the industrial controller 15 is programmed using an object-oriented programming language. The program terminal 20 is stored in the memory 17 of the industrial controller 15 and can be interfaced with the industrial controller 15 to change, add or delete various objects used to implement its functions. Objects maintained in the memory to realize the functions of the industrial controller 15 can be collectively referred to as a control program for the industrial controller. Accordingly, the program terminal 20 provides a program interface for updating the control program of the industrial controller 15.

  The scanner 50 interfaces with the I / O module 30 to collect input data during the update interval, consolidates the data into a single optimized connection packet 100 shown in more detail in FIG. The connection packet 100 is transferred to the industrial controller 15. The particular interval between updates (eg, optimized control packet 100) can vary depending on the particular implementation. The scanner 50 transmits output data from the industrial controller 15 to the I / O module 30 and changes the state of one of the controlled actuators 45 based on the calculation of the control program for the previous input data.

  The scanner 50 can use various techniques to collect data from the I / O module 30. For example, the scanner 50 can poll the I / O module 30 periodically to request the latest data value for each parameter being monitored. An I / O module 30 that has not generated new data will respond with the previous data value. In contrast, the I / O module 30 can set a flag whenever new data is generated. Scanner 50 monitors this flag and requests data during the update interval only when the flag is set (i.e., this flag is cleared after transfer). In yet another technique, the I / O module 30 can send data to the scanner 50 when the module occurs (eg, synchronously or asynchronously). This technique can result in additional traffic between the scanner 50 and the I / O module 30, which only receives connection packets 100 that are optimized by the industrial controller 15 at the expected interval. The industrial controller 15 is not affected as if it were. In the case of an analog module (for example, one of the I / O modules 35), data can be continuously used for the scanner 55.

  Reference is now made to FIG. Here, a diagram illustrating an interface between the industrial controller 15 and the scanner 50 for transmitting the optimized connection packet 100 is shown. The optimized connection packet 100 is an unstructured block of data that represents data collected from each of the I / O modules 35. Data from each I / O module 30 is linked in a predetermined order without formatting.

  In the illustrated example, two of the I / O modules 35, referred to as Module 1 and Module 2, are associated with motor drives, which in turn provide drive signals to the motor. The motor drive exchanges speed data with the industrial controller 15 by means of an optimized connection packet 100. Tables 1 and 2 below show examples of data structures for data elements of speed control data. Table 1 shows format information for each of the elements of the rate control data, and Table 2 shows the data objects in the I / O module 30 in the data block so that they are included in the optimized connection packet 100. Shows how to assemble. In the case of the scanner 55, data objects (representing buffers in the I / O module) are concatenated by the scanner 55 into a single I / O data block for the I / O module 35.

The data object of the I / O module 30 indicates the configuration and state of the I / O module 30. Data blocks for all of the I / O modules 30, 35 are concatenated to form an optimized connection packet 100. Data structures and data block formats are described for illustration only, and the application of the present invention is not limited to a particular data structure or format.

  As shown in Table 1, the speed control data is a logic flag (AtSpeed) that indicates whether the motor is operating at the desired speed, a logic flag that indicates whether a torque reference is provided locally or through the network. (RefFromNet), a logic flag (ControlFromNet) indicating whether the motor drive is controlled locally or through the network, a logic flag (Ready) indicating whether the motor drive is ready, the motor is operating in the reverse direction A logic flag (Running Reverse) indicating that the motor is running forward, a logic flag (Running Forward) indicating that the motor is operating in the forward direction, and a logic flag (Faulted) indicating whether the motor drive is in a fault state Including. One flag (pad) is reserved for future use. The speed control data also includes a reserved 1-byte field (pad), of which 1 byte is for the least significant bit of motor speed (SpeedActualRPM) and 1 byte is for the most significant bit of motor speed. Since the rate control data for the two modules is simply concatenated in the optimized connection packet 100, the result is a stream of bits that includes the rate control data for each module. Thus, each data object for the I / O module is in a predetermined manner, but is arbitrarily offset within the optimized connection packet 100.

  Assuming that the optimized connection packet 100 starts with data for module 1, then data from the other module follows, then data for module 2, then bits 0-31 (i.e. block 115) indicates the speed control data for module 1, and bits 628-659 (ie, block 120) indicate the speed control data for module 2.

  Although only one data block 115, 120 is shown for each I / O module 30, multiple data blocks can be used. For example, output data or configuration data for the I / O module 30 may be included in a separate block from the input data. Further, the input data may be separated into separate data blocks, where each data block is associated with one of the buffers on the I / O module 30.

  The industrial control system 10 uses cast tags 125 that reference individual blocks 115, 120 in the optimized connection packet 100. In general, the cast tag 125 provides a logical reference to a portion of the optimized connection packet 100 that includes data objects for a particular I / O module 30. The logic 130 in the industrial controller 15 can use the cast tag 125 instead of a hard reference for individual bits of the optimized connection packet 100.

  In a typical industrial control environment, a single tag can be used to reference a single data area. A tag generally includes a name or symbol, a data type that specifies the name and data format of the member, and a data object that references a specific physical location of the data set. A data object for a conventional tag represents the entire data set and generally only one tag refers to a particular data object.

  The cast tag 125 is different from the conventional tag in the following points. That is, the data object of the cast tag refers to only a subset of the data set, and differs from the conventional tag in that the data type is superimposed on the portion of data to which the tag refers. Multiple cast tags 125 can reference different subsets of the data set for different I / O modules 30 and impose their own independent data types on that data. From a programming perspective, tags appear to be independent. Accordingly, each cast tag 125 refers to one I / O data in the I / O module 30, and members defined by the cast tag 125 are individual data stored in a buffer in the I / O module 30. Refers to an element.

  The structure shown in Table 1 above shows the data tag used in the cast tag 125 to specify the data format for the data elements of the member and rate control data. Therefore, in AtSpeed of module 1 of cast tag 125, module 1 is a symbol, and AtSpeed is defined as one of data type members in a logical format. The data object refers to bit 7 of the optimized connection packet 100.

The following pseudocode examples shown in Tables 3 and 4 show how the programmatic reference using the cast tag 125 differs from the previous hard reference command. This pseudo code does not show the actual code used, but rather shows only the advantages gained by the cast tag 125 through a hard reference.

  As is apparent from the example in Table 3, it is possible to refer to the parameters of the associated I / O module 30 by the cast tag 125 without knowing the instructions used by the scanner 50 to concatenate the data. ing. Furthermore, the cast tag 125 specifies a data format, which may not be included in the programmatic reference.

  Referring to FIG. 1, the cast tag 125 is instantiated and maintained by the programming terminal 20 and can be used within the programming environment to generate a control program for the industrial controller 15. In the programming environment, the data for each I / O module 30 appears to be independent and each member can be referenced by name in the logic. The cast tag 125 is also stored in the industrial controller 15.

  In some cases, the control program may be compiled before loading the control program into the industrial controller 15, and the reference is converted to a physical reference in the compiled code. However, if the organization of the optimized connection packet 100 used by the scanner 50 changes (eg, due to the addition or deletion of the I / O module 30), only the cast tag 125 must be updated. The control program can then be recompiled and the new reference specified by the cast tag 125 is incorporated into the compiled code. Therefore, no change is necessary in the control program. In another case of decoding the control program, the cast tag 125 can be referenced directly in the control program.

  Since the industrial controller 15 stores the cast tag 125, other entities in the industrial control system 10 also use the logical reference created by the cast tag 125 to refer to the module data stored by the industrial controller 15. it can. For example, the HMI 25 can query the industrial controller 15 to determine if the motor associated with module 1 is at a speed that uses the module 1 AtSpeed reference. In addition, the HMI 25 can include its own code that can be operated to continuously display the motor status associated with modules 1 and 2 on its display. The HMI code need only use the AtSpeed reference of module 1 and the AtSpeed reference of module 2 to access the status information. When the organization of the optimized connection packet 100 changes, the code of the HMI 25 may not be changed.

  The cast tag 125 can also be used to reconfigure the control program. For example, if a programming terminal, such as a field programming terminal implemented in a notebook computer, except for the programming terminal 20 shown in FIG. It is also possible to determine the structure of the optimized data packet 100 and analyze the control program code.

  Using the cast tag 125 greatly simplifies the development and maintenance of codes used in the industrial control system 10. Even if the organization of the optimized connection packet 100 is changed, the code may not be changed, and only the cast tag 125 is updated. In addition, once the cast tag 125 is defined, the user does not have to access an external document describing the connection packet 100 mapping optimized for accessing the module data in the industrial control system 10, so that It can easily interface with the industrial control system 10.

  The particular embodiments disclosed so far are merely illustrative and the invention will be apparent to those skilled in the art who may benefit from the subject matter described herein, and will be different and equivalent. The present invention can be modified or implemented. Furthermore, there is no intention to limit the invention to only the details of construction or design shown herein other than construction or design described in the claims. It is therefore evident that the particular embodiments disclosed so far can be varied or modified and all such variations are considered to fall within the scope of the paper of the present invention. Therefore, the protection scope required in this specification is described in the claims.

1 is a simplified block diagram of an industrial control system according to an illustrated embodiment of the present invention. FIG. 2 shows an interface between an industrial controller and a scanner for transmitting optimized connection packets.

Explanation of symbols

15 Industrial Controller 16 Processing Unit 17 Memory 20 Programming Terminal 25 Human-Machine Interface 30 I / O Module
35 I / O module 40 Sensor 45 Actuator 50 Scanner 55 Scanner 125 Cast tag

Claims (1)

An I / O module (30) operable to interface with and exchange I / O data with the process;
Optimized connection that exchanges I / O data with the I / O module (30) and includes I / O data for each module located in the unformatted data block (115, 120) A scanner (50, 55) operable to communicate using a packet (100);
The optimized connection packet (100) is exchanged with the scanner (50, 55), and the I / O data included in the optimized connection packet (100) is used to control the process. And an industrial controller (15) operable to store a plurality of cast tags (125), wherein each cast tag (125) An unformatted data block (115,) associated with one of the O modules (30) and including at least a portion of the I / O data for the associated I / O module (30) An industrial control system (10) that provides a logical reference to a subset of 120).

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